Maricopa County · Arizona · EPA SDWIS 2026Q2
Gilbert Water Quality
What's in Gilbert's water
PFAS (forever chemicals)
2.5×above guideline
Detected above the EPA's 4 ppt limit for PFOA/PFOS — the "forever chemicals" linked to cancer and immune effects. Compounds found: PFBA, PFBS, PFHxA, PFOA, PFOS, PFPeA.
Total Trihalomethanes (TTHM)
Violation on record
5 EPA violations on record (most recent 2023). TTHM form when chlorine used to disinfect water reacts with natural organic matter. Long-term exposure has been linked to increased cancer risk and to harm in pregnancy. Levels often rise in warmer months and in systems with more organic material.
Arsenic
Violation on record
14 EPA violations on record (most recent 2025). Arsenic is a naturally occurring element that dissolves into groundwater from rock and is also released by mining and industry. Long-term exposure is associated with several cancers and with skin, cardiovascular, and developmental harm. It is common in parts of the Southwest.
Nitrate
Violation on record
11 EPA violations on record (most recent 2025). Nitrate enters water mainly from fertilizer runoff, septic systems, and animal waste. High levels can interfere with the blood's ability to carry oxygen, a special danger for infants. Long-term low-level exposure has also been linked to elevated cancer risk in some studies.
Cadmium
Violation on record
2 EPA violations on record (most recent 2021). Cadmium enters water from corroded galvanized pipes and from industrial and mining discharges. Long-term exposure mainly damages the kidneys and can weaken bones. It is toxic even at low levels over time.
Mercury
Violation on record
2 EPA violations on record (most recent 2021). Mercury reaches water from natural deposits, industrial runoff, and discarded products. Long-term exposure harms the kidneys and nervous system. It is tightly regulated because of its toxicity at low concentrations.
Fluoride
Violation on record
2 EPA violations on record (most recent 2021). Fluoride occurs naturally in groundwater and is also added by many utilities to reduce tooth decay. At high natural levels it can damage developing teeth and, over long exposure, weaken bones. The federal limit targets these high-level health effects rather than the low levels used for dental benefit.
Haloacetic Acids (HAA5)
Violation on record
2 EPA violations on record (most recent 2023). HAA5 are a second group of chlorine disinfection byproducts formed when chlorine reacts with organic matter in water. Long-term exposure is associated with increased cancer risk and possible developmental effects. They commonly occur together with trihalomethanes.
Selenium
Violation on record
2 EPA violations on record (most recent 2021). Selenium is a naturally occurring element that is a necessary nutrient at trace levels but toxic in excess. Long-term high exposure can damage the nervous system, hair, and nails. It enters water from natural deposits and from irrigation drainage.
PFOA
Violation on record
2 EPA violations on record (most recent 2021). PFOA is a long-lived "forever chemical" once used to make nonstick and stain-resistant products. It builds up in the body over time and is associated with certain cancers, immune effects, and developmental harm. EPA finalized a strict drinking-water limit for it in 2024.
Barium
Violation on record
2 EPA violations on record (most recent 2021). Barium dissolves into water naturally from rock and can also come from drilling and industrial discharges. Drinking elevated levels over time can raise blood pressure and stress the cardiovascular system. It is fairly common in some groundwater sources.
Atrazine
Violation on record
1 EPA violation on record (most recent 2021). Atrazine is one of the most widely used weed killers and reaches water through agricultural runoff. It is an endocrine disruptor associated with reproductive and developmental effects, and concentrations tend to spike seasonally after application. It is most common in farming regions.
PFOS
Violation on record
1 EPA violation on record (most recent 2021). PFOS is another "forever chemical" from older firefighting foams and consumer coatings. Like PFOA it accumulates in the body and is linked to immune, thyroid, liver, and developmental effects. EPA set an enforceable limit for it in 2024.
Water hardness
very hard
Gilbert's water is very hard. Hardness isn't a health risk, but it drives scale on fixtures and water heaters, shortens appliance life, and leaves skin and hair dry.
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- PWSID
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